Multi-indicia display device

ABSTRACT

A multi-indicia display device includes a rigid base plate made up of a plurality of sheets of an electrical insulating material laminated together. Electrodes are mounted on the base plate. One of the electrodes is a metal layer coated on the base plate forming a plurality of separate but identical indicia, each indicia comprising a plurality of sections. Metal layer termination pads are coated on the front and back surfaces of the base plate along one edge thereof. Metal film electrical circuitry is coated on the surfaces of the sheets of the base plate and extend through holes in the sheets to electrically connect the electrodes to the termination pads. A transparent cover is mounted on the base plate and extends over the electrodes.

United States Patent [191 Farina MULTl-llNDIClA DISPLAY DEVICE [75] lnventor: Patrick Louis Farina, Somerville,

[73] Assignee: RCA Corporation, New York, N.Y.

[22] Filed: June 14, 1 972 [21] Appl. No.: 262,486

[52] U.S. Cl 313/108 R, 313/109.5, 313/217,

313/220 [51 int. Cl HOlj 61/66, HOlj 63/02 [58] Field of Search 313/1095, 210, 217, 108 A, 313/108 R, 220

1/1973 Skutt 313/1095 6/1973 Kupsky et a1. 313/1095 Primary Examiner--Palmer C. Demeo Attorney, Agent, or FirmG. H. Bruestle; l. M. Krittman [5 7] ABSTRACT A multi-indicia display device includes a rigid base plate made up of a plurality of sheets of an electrical insulating material laminated together. Electrodes are mounted on the base plate. One of the electrodes is a metal layer coated on the base plate forming a plurality of separate but identical indicia, each indicia comprising a plurality of sections. Metal layer termination pads are coated on the front and back surfaces of the base plate along one edge thereof. Metal film electrical circuitry is coated on the surfaces of the sheets of the base plate and extend through holes in the sheets to electrically connect the electrodes to the termination pads. A transparent cover is mounted on the base plate and extends over the electrodes.

13 Claims, 7 Drawing Figures PATENTED MARZS I974 SHEET 1 OF 3 Fig. 1.

BACKGROUND OF THE INVENTION The present invention relates to a multiindicia luminescent display device of the electroluminescent or gas discharge type. More particularly, the present invention relates to such a display device which is rigid, compact, which can be easily made up with a variety of indicia and which can be easily plugged into a desired operating circuit.

There are various devices, such as calculators, weighing scales, clocks and the like, which use digital readout displays. Recently these devices, which previously operated mechanically or electromechanically, have been made with complete electronic operation. To complement the electronic operation of these devices it became necessary to have an electronic read-out display. Initially, these electronic read-out displays were made up of a plurality of display tubes each of the type shown in US. Pat. No. 3,594,602 to N. Lindburg, issued July 20, 1971, entitled Display Device Including Resilient Mounting Means. However, as these devices have been made smaller in size it has been found that the multiple tube displays are not only too large for the size of the device but also require considerable wiring to connect the individual tubes in the electronic circuit of the device. Therefore, it has become desirable to have a multi-indicia display which is small and compact and which can be easily connected into the electronic circuit of the device. Also, it is desirable that the display have flexibility as to the indicia provided by the display so that a single basic construction can be used to make displays for various purposes. In addition, it is desirable that the display be capable of operating at the low power levels of the integrated circuit type electronic circuits being used in the devices that use the displays.

SUMMARY OF THE INVENTION A display device includes a rigid base plate of a plurality of sheets of an electrical insulating material bonded together in face-to-face relation. A metal film first electrode is coated on the front face of the front sheet of the base plate. The first electrode forms a plurality of identical indicia, each indicia comprising a plurality of sections disposed in preselected positions. A plurality of metal film interconnecting strips are coated on the back surface of the from sheet of the base plate. Each of the interconnecting strips is electrically connected through said front sheet of the base plate to the similarly positioned sections of each of the indicia. Second electrodes are mounted on the front surface of the base plate and extend over the first electrode. Metal film termination pads are coated on the front and back surfaces of the base plate along one edge of the base plate. Metal film electrical circuit means are coated on the surfaces of the sheets of the base plate and extend through the sheets to electrically connect the interconnecting strips and the other electrodes to the terminal pads. A transparent cover plate is mounted on the front surface of the base plate and forms a chamber with the base plate which contains the electrodes.

BRIEF DESCRIPTION OF DRAWINGS FIG. I is an exploded perspective view of one form of the display device of the present invention.

FIG. 2 is a sectional view of an assembled display device.

FIG. 3 is an enlarged view of one of the indicia of the display device.

FIGS. 4-7 are plan views of the surfaces of the individual sheets of the base plate of the display device.

DETAILED DESCRIPTION Referring to FIGS. 11 and 2, a form of the display device of the present invention is generally designated as 10. The display device 10 comprises a base plate 12 having a plurality of indicia forming means on its front surface, a plurality of grids 14 (one for each indicia), a cathode assembly 16, a getter l8, and a transparent cover 20. As shown, the indicia are a plurality of identical sectioned patterns 22a-22h each of which is adapted to form any digit between 0 and 9 as well as the plus and minus symbols and certain letters of the alphabet. The display device 10 will first be described as an electroluminescent device.

The base plate 12 is a flat rectangular plate of a rigid electrical insulating material, preferably a ceramic, having a mounting and terminal portion 12a projecting from its lower edge. As shown in FIG. 2, the base plate 12 comprises two sheets 24 and 26 firmly bonded together in face-to-face relation. As shown in FIG. 4, on the front surface of the front sheet 24 are the indicia 22a-22h arranged in a row in spaced side-by-side relation along with the width of the sheet 24. As shown in FIG. 3, each of the indicia 22a-22h is made up of seven spaced, bar-shaped sections or areas 28, 30, 32, 34, 36, 38 and 40, arranged in two end-to-end substantially square or parallelogram shaped patterns having a common side, the section 34, so as to delineate the block digit 8. Two additional bar-shaped sections or areas 42 and 44 extend between the middle section 34 and each of the top and bottom sections 28 and 40, respectively, parallel to the side sections. As shown in FIG. 2, the sections of the indicia 22a-22h comprise an electrode layer 46 of an electrically conductive metal, such as molybdenum which can be coated with nickel, coated on the front surface of the front sheet 24 and a phosphor layer 48 coated over the electrode layer 46. The phosphor layer 48 may be of any well known electroluminescent phosphor material, such as zinc activated zinc oxide phosphor.

As shown in FIG. 4, circular dot areas 50 are on the front surface of the front sheet 24. The dot areas 50 are positioned just below the space between the bar sections 38 and 40 respectively of the indica 22a-22h. Each dot area 50 also comprises an electrode layer 46 coated on the front surface of the front sheet 24 and a phosphor layer 48 coated on the electrode layer 46. A connecting strip 51 of an electrically conductive metal is coated on the front surface of the front sheet 24. The connecting strip 51 is an extension of the electrode layers 46 of the dot areas 50 and extends therebetween so as to electrically connect the dot areas together.

Two parallel rows of rectangular mounting pads 52 and 54, each of a layer of an electrically conductive metal, are coated on the front surface of the front sheet 24. The mounting pads 54 are positioned parallel to but spaced above the indicia top sections 28, and the mounting pads 54 are positioned parallel to but spaced below the indicia bottom sections 40. Termination pads 56a-56k, each of an electrically conductive metal are coated on the front surface of the front sheet 24. The

termination pads 56a-56k are spaced, parallel rectangular areas which extend along the mounting and termination portion 12a of the base plate 12 perpendicular to the bottom edge of the mounting and termination portion. A getter mounting pad 57 of a film of an electrically conductive metal is coated on the front surface of the front sheet 24 just above the termination pad 56f.

Nine sets of a plurality of holes (FIG. 58, 60, 62, 64, 66, 68, 70, 72 and 74 are provided through the front sheet 24. The holes of each set are arranged in a row across the front sheet 24 with the rows of the holes being spaced, parallel relation. The top row of holes 58 open onto the front surface of the sheet 24 closely spaced or juxtaposed to the upper edge of the upper sections 28 (see FIG. 3). The next row of holes 60 are juxtaposed to the side sections 32 at the upper ends thereof. The holes 62 are juxtaposed to the upper additional sections 42 intermediate the ends thereof. The holes 64 are juxtaposed to the side sections 30 at the lower ends thereof. The next row of holes 66 are juxtaposed to the lower edge of the middle sections 34. The holes 68 are juxtaposed to the lower additional sections 44 adjacent to but spaced from the upper ends thereof. The holes 70 are juxtaposed to the side sections 38 adjacent to but spaced upperwardly from the lower ends thereof. The holes 72 are juxtaposed to the side sections 36 at the lower ends thereof. The bottom row of holes 74 are juxtaposed to the lower edges of the bottom sections 40. Each of the holes is filled or coated with an electrically conductive metal which contacts the metal electrode layer 46 of the adjacent indicia section.

As shown in FIG. 5, on the back surface of front sheet 24 are nine interconnecting strips 76, 78, 80, 82, 84, 86, 88, 90, and 92 of an electrically conductive metal which extend in spaced parallel relation across the back surface. The top strip 76 extends across the holes 58 and contacts the metal in the holes so as to electrically connect together all the indicia top sections 28. Similarly, the strips 78, 80, 82, 84, 86, 88, 90 and 92 extend across the holes 60, 62, 64, 66, 68, 70, 72 and 74 respectively so that the similar sections of each of the indicia 220-2211 are electrically connected together. The interconnecting strips 80 and 86 are connected together at their ends to that the spaced apart sections 42 and 44 of each indicia are electrically connected together.

Holes 94 (FIG. 5) extend through the from sheet 24 with each of the holes intersecting (FIG. 4) the bottom edge of a different one of the bottom mounting pads 54. Holes 96a-96k extend through the front sheet 24 with each of the holes being intersecting the top end of a separate one of the termination pads 56a-56k. A hole 97 extends through the front sheet at the getter mounting pad 57. Each of the holes 94, 96a96k and 97 is filled or coated with an electrically conductive metal which contacts the intersected or adjacent mounting pad or termination pad. Holes 98a and 98b extend through the front sheet 24 slightly below the bottom mounting pads 54 and above the termination pads 56c and 56e respectively. As shown in FIG. 5, on the back surface of the front sheet 24 are coated interconnecting metal strips 100 each of which extends from a separate one of the holes 94 to a separate one of the holes 96a, 96b, 96d, 966:, 96g, 96h, 96j and 96k, respectively. Thus, each of the mounting pads 54 is electrically connected to a separate one of the termination pads 56a, 56b, 56d, 56e, 56 g, 56h, 56j and 56k, respectively. Interconnecting strips 102a and 102b are coated on the back surface of the front sheet 24. The interconnecting strip 102a extends between the holes 98a and 960, and the interconnecting strip 102b extends between the holes 98b and 96i. A hole 104 extends through the front sheet 24 just above the termination pad 56k, and a metal film interconnecting pad 106 is coated on the back surface of the front sheet and extends over the hole 104. A hole 108 extends through the front sheet 24 juxtaposed to the dot area interconnecting strip 51 and is filled or coated with a metal. A small metal film interconnecting pad 110 is coated on the back surface of the from sheet and extends over the hole 108. A pair of spaced holes 112a and 112b extend through the front sheet 24 above the top mounting pads 52. The hole 1120 is filled or coated with a metal, and a metal film interconnecting pad 114 is coated on the back surface of the front sheet and extends over the hole 112a. A metal film connecting pad 115 is coated on the back surface of the front sheet 26 and extends between the hole 97 and the hole 96f so as to electrically connect the getter mounting pad 57 to the termiantion pad 56f.

The back sheet 26 of the base plate 12 has holes 1l6a-1l6h therethrough as shown in FIGS. 6 and 7. The holes 116a116h are filled or coated with a metal which extends onto the front surface of the back sheet 26 around each of the holes. The holes 116a-1l6h are positioned on the back sheet 26 so that when the two sheets 24 and 26 are bonded together the metal in the holes ll6a116h contact a separate one of the indicia section interconnecting strips 76, 78, 80, 82, 84, 88, 90 and 92 respectively. The back sheet 26 also has holes 118, 120 and 122 therethrough, which holes are filled or coated with a metal which extends onto the front surface of the back sheet around the holes. The holes 118, 120 and 122 are positioned so that the metal therein contacts the interconnecting pads 106, 110 and 114 respectively. Spaced metal film termination pads 124a-l24k are coated on the back surface of the back sheet 26. The termination pads 12441-124 k extend across the back sheet from and substantially perpendicular to the bottom edge of the mounting and termination portion to and across separate ones of the holes in the back sheet. The termination pads 124a, 124b and 124k extend to the holes 118, 120 and 122 respectively. The termination pads l24c124j extend to the holes 116b, 116a, 116d, 116/1, 116g, 116e, 1160 and 116f respectively. Thus, the termination pads l24c-l24j are each electrically connected to a separate set of the indicia sections through the indicia section interconnecting strips, and the termination pad l24b is electrically connected to the dot areas 50.

A process of fabricating the base plate 12 is as follows. Two sheets of ceramic material from which the base plate 12 is eventually formed, are prepared in the unfired or green" state. The various holes are punched through each of the sheets. The metal electrode layers, mounting pads, termination pads, interconnecting strips and interconnecting pads are then applied to the sheets, such as by the well known process of screen printing. When the metal layers are applied to the sheets some of the metal material is forced through the holes to fill or coat the holes. The sheets are then placed in face-to-face relation and heated under pressure to bond the sheets together. The laminated sheets are then fired in an inert atmosphere at a temperature to harden the ceramic material, about l,600 C. The exposed metal is then coated with a suitable electrically conductive metal to which the phosphor will adhere, such as nickel. The phosphor layer 48 is then coated on the front surface of the front sheet 24, such as by screen printing, and fired to remove binders.

The grids 14 (FIG. 1) each comprises a rectangular, metal screen 126 having U-shaped mounting brackets 128a and 128b at each end thereof. The ends of the screen 126 are secured to the upper legs of the mounting brackets 128a and 128b. Each of the screens 126 extends across a separate one of the indicia 22a-22h in spaced, parallel relation thereto with the lower leg of the mounting bracket 128a being seated on a top mounting pad 52 and the lower leg of the mounting bracket 1281) being seated on a bottom mounting pad 54 respectively. The mounting brackets are electrically and mechanically secured to their respective mounting pads, such as by brazing or soldering. Thus, each of the grids 14 is mechanically mounted in the base plate and electrically connected to a separate one of the termination pads 56a, 56b, 56d, 56c, 56g, 56h, 56j and 56k.

The cathode assembly 16 comprises a first mounting wire 130 and second and third longitudinally aligned mounting wires 132 and 134 in spaced parallel relation to the mounting wire 130. A plurality of fine cathode wires 136 are connected in spaced parallel relation between the first mounting wire 130 and the second and third mounting wires 132 and 134. The number of the cathode wires 136 is at least equal to the number of the indicia. In the form shown there are eight cathode wires, four of which are connected between the first mounting wire 130 and the second mounting wire 132, and the other of which are connected between the first mounting wire 130 and the third mounting wire 134. The first mounting wire 130 has a pair of spaced support posts 138a and 13812 which are secured within the holes 112a and 1121: respectively in the base plate 12. The second mounting wire 132 has a support base 140 which is secured within the hole 980 in the base plate 12. The third mounting wire 134 has a support post 142 which is secured within the hole 98b in the base plate. Thus, the cathode assembly 16 is mounted on the base plate 12 with the mounting wires 130 and 132 and 134 extending across the base plate along opposite ends of the indicia and each of the cathode wires 136 extending across a separate one of the indicia above the grids 14. The first mounting wire 130 is electrically connected to the termination pad 124k on the back surface of the base plate through the interconnecting pad 114 and hole 122. The second mounting wire 132 is electrically connected to the termination pad 560 through the interconnecting strip 102a and the third mounting wire 134 is electrically connected to the termination pad 561' through the interconnecting strip 10212.

The getter 18 is a tubing 144 filled with a suitable gettering material and connected between support posts 146 and 148. The support post 146 is secured in the hole 104 so as to be electrically connected to the termination pad 124a through the interconnecting pad 106 and hole 118. The support post 148 is secured in the hole 97 so as to be electrically connected to the termination pad 56f. Thus, the getter 18 is electrically connected between the termination pads 124a and 56f.

The cover 20 is a rectangular, cup-shaped body of a transparent material, such as glass, of a size corresponding to that of the base plate 12. The cover 20 is seated on the front surface of the base plate 12 (FIG. 2) around the edge thereof so as to form with the base plate a chamber which contains the indicia 22a-2h, the grids 14, the cathode assembly 16 and the getter 18. The cover 20 is secured to the base plate 12 by a layer 150 of a suitable bonding material, such as a glass cement. However, the mounting and terminal portion 12a of the base plate 12 projects beyond the edge of the cover 20 so as to expose the termination pads 56a-56k. An exhaust tube 152 extends through and is secured in a hole 154 in the base plate 12. The interior of the chamber between the cover 20 and base plate 12 is evacuated through the exhaust tube 152 which is then sealed, such as by pinching, to hermetically seal off the chamber. A protective layer 156 of an electrical insulating material, such as a plastic or ceramic, is provided over the back surface of the base plate 12 as shown in FIG. 2. However, the mounting and terminal portion 12a is not so coated so as to leave the termination pads 124al24k exposed. The protective layer 156 may be a coating applied to the back surface of the base plate 12 or may be a third sheet of the ceramic material fired and bonded to the base plate when the sheets 24 and 26 of the base plate are bonded together.

In the operation of the display device 10, the mounting and terminal portion 12a of the base plate 12 is plugged into a socket having a separate contact for each of the termination pads 56a-56k and l24a124k. The termination pads connected to the electrode layers of the indicia 22a-22h and the dot areas 50 and the cathode wires 136 are connected across a source of DC. voltage so that the electrode layers serve as anodes and the cathode wires as cathodes for each of the indicia. The termination pads connected to the electrode layers of each of the indicia sections and the dot areas are connected to such voltage source through suitable switching circuitry to allow the voltage to be applied to one or more of the various indicia sections and dot areas as desired.

The termination pads connected to the grids 14 are connected through suitable switching circuitry to a DC. voltage source such that each grid can be switched in consecutive sequence between an off condition, i.e., the grid being biased negatively with respect to the cathode wires, and an on condition, i.e., the grid being biased at a voltage similar to the anode voltage.

The display device is operated in a multiplex mode, wherein each of the indicia 22a-22h is individually lit up in consecutive sequence from one side of the display to the other.

To light up the first indicia 22a, the sections of the indicia which are to form the desired numeral are turned on, i.e., connected to the voltage source. For example, to form the digit 8 in the first indicia 22a, the sections 28, 30, 32, 34, 36, 38 and 40 are turned on. Since all the various sections of all the indicia are connected in parallel, all the sections of all the indicia are thus turned on. The grid 14 over the first indicia is turned on, i.e., a voltage similar to the anode voltage is applied that, while the other grids are left off, i.e., have a voltage thereon which is negative with respect to the cathode wires 36. This allows electrons to flow from the cathode wire 36 over the first indicia 22a through the grid 14 to the turned on anode sections of the first indicia 220. These electrons bombard the phosphor layer over the tumed-on anode sections causing the phosphor sections to luminesce and thereby light up the desired digit on the first indicia 22a. However, the turned-off grids over the other indicia prevent the electrons from the cathode wires 36 from passing to the anode sections of the other indicia so that there is no luminescence from the other indicia.

The voltages applied to the anode sections are then changed to turn on the anode sections which are desired for the digit of the second indicia 22b. For example to form the digit, 7, the anode sections 28, 32 and 38 are turned on. The grid 14 over the second indicia 22b is turned-on and the grid over the first indicia 22a is turned off along with the grids over the indicia 22c-22h. This allows electrons to flow from the cathode wire 36 over the second indicia 22b to the turnedon sections of the second indicia. The electrons bombarded the phosphor layer on the turned-on anode sections of the second indicia 22b causing the phosphor layer sections to luminesce and thereby light up the digit 7." However, since the grids 14 over the other indicia are turned off the digit 7 is not lit up on the other indicia. Similarly each of the indicia is activated in consecutive sequence to light up a desired digit on each of the indicia until the cycle is completed at the last indicia 2211. To provide a decimal point between any two indicia, the anode of the dot areas 50 is turned on at the appropriate time to light up the phosphor layer over the desired dot area.

During each cycle of operation of the display device 10, each indicia is lit up in sequence. By rapidly repeating the cycle of operation so that each indicia is lit up a number of times during a short period oftime, the display device will have the appearance to the eye of having all of the indicia lit up at once. Thus, the display device is preferably operated at a cycle repetition rate high enough to provide a flicker free appearance of all the indicia lit up at once, preferablyabout 40 cycles per second. iiwvz'rjaarifig any cycle of operation the digit for any of the indicia can be changed by changing the anode areas which are turned on. Thus the display device can provide any desired series of digits which can be maintained or changed as desired by the switching circuitry through which the display device is connected to the operating voltage sources.

The display device 10 shown can readily be modified to provide a gas discharge type of device. For this type of use, the phosphor layer 48 and the cathode assembly 16 are left off and the chamber between the cover 20 and the base plate 12 is filled with a suitable gas, such as neon under pressure. Also, it is desirable that the dot area interconnecting strip 51 be placed on the back surface of the front sheet 24 of the base plate 12 and connected to each of the dot areas 50a-50h by metal coated or filled holes. The termination pads for the indicia sections and the grids are connected through suitable switching circuitry to a voltage source such that the indicia sections are the cathode electrodes and the grids are the anode electrodes of the device. In the multiplex mode of operating the gas discharge type of display device the indicia sections which are to form the digit of the first indicia are turned on and the grid over 6 the first indicia is turned on. A sufficient voltage difference between the on grid anode and the on indicia cathode sections is provided to break down the gas and cause the turned on cathode sections to glow in the form of the desired digit. The indicia sections are then switched to turn on the sections to form the digit of the second indicia. The first grid is turned of and the second grid is turned on. A voltage difference between the turned on second grid and the turned on indicia sections causes the gas to breakdown and the turned on sections of the second indicia to glow in the form of the desired digit. Similarly, the turned on sections of each of the indicia are caused to glow in the desired digit in consecutive sequence. Thus, during each cycle of operation luminescent digits are provided by each indicia in sequence and the cycle is repeated at a rate sufficient to provide the appearance of having all of the digits being lit up simultaneously.

Thus, there is provided by the present invention a multi-indicia display device in which the indicia electrodes are mounted on a surface of a multi-layer base plate with one of the electrodes being a metal layer in the form of sectional indicia and a cover is mounted on the base plate to enclose the electrodes. The electrodes are electrically connected by circuitry coated on and extending through the layers of the base plate to termination pads extending along an edge of the base plate. This provides a display device which is small and compact and which can be easily connected to an electronic circuit for operating the display device by plugging the mounting and terminal portion 12a directly into a terminal socket. The display device 10 has flexi' bility as to the indicia provided by the device since the sectional indicia can take any desired form. In addition to the digits shown, the indicia can be in the form of letters or any desired symbol. For example, for a display device for an electronic clock, the third and sixth indicia 22c and 22fcan each be in the form ofa colon symbol. Thus, the first two indicia will indicate the hour, the fourth and fifth the minute and the last two the second. Also, if desired, the last two indicia can be replaced by the letters A.M. and/or P.M. to indicate the proper time. No matter what form the indicia takes, the sections of the indicia can be electrically connected to termination pads by the circuitry on and extending through the base plate. The display device 10 is capable of being operated at relatively low power loads so that it can be operated through integrated circuit type switching circuits. In fact, if desired, the integrated circuit type devices, which are very small in size, can be mounted directly on the back of the base plate so as to combine the switching circuitry directly with the display device. In addition, to more clearly delineate the luminated indicia, a mask may be placed over each of the indicia with the mask having openings therethrough corresponding to the shape of the sections of the indicia. In the electroluminescent type of display device 10, each of the masks can be mounted directly under a grid 14. In the gas discharge type of display device, each of the grids 14 may be in the form of a metal mask instead of the wire mesh.

I claim:

1. A display device comprising:

an insulating laminated substrate having a plurality of lamina of insulating material bonded in face-toface relation,

a patterned first electrode on a front lamina surface of said substrate forming a plurality of indicia,

a plurality of second electrodes mounted on said substrate disposed one each in spaced relation over each of said indicia,

metallized paths extending along various inside facing lamina surfaces of said substrate,

metal termination pads on a lamina surface in spaced relation to said metallized paths terminating along one edge of said substrate, and

connection means extending through the lamina providing interconnections between various ones of said terminal pads and various ones of said indicia and said electrodes via said metallized paths.

2. A display device comprising:

a rigid base plate of a plurality of sheets of an electrical insulating material bonded together in face-toface relation;

a metal film first electrode coated on the front face of the front sheet of the base plate, said metal film electrode forming a plurality of identical indicia, each of said indicia comprising a plurality of sections disposed in pre-selected positions;

a plurality of metal film interconnecting strips coated on an inside surface of one of said sheets of the base plate, each of said interconnecting strips being electrically connected through said front sheet to the similarly positioned electrode section of each of the indicia;

second electrodes mounted on the front surface of the base plate and extending over the first electrodes;

metal film termination pads coated on the base plate and terminating along one edge of the base plate;

metal film electrical circuit means coated on the surface of the sheets of the base plate and extending through the sheets electrically connecting the interconnecting strips and the second electrodes to the termination pads; and a transparent cover mounted on the front surface of the base plate and forming a chamber with said base plate which contains the electrodes.

3. A display device in accordance with claim 2 including a layer of an electroluminescent phosphor coated over the sections of the first electrode and a plurality of grids mounted on the front surface of the base plate with each of said grids extending over a separate one of the indicia of said first electrodes and under a second electrode.

4. A display device in accordance with claim 3 including electrical circuits means on the surfaces of and extending through at least one of the sheets of the base plate electrically connecting each of said grids to a separate termination pad on said base plate.

5. A display device in accordance with claim 4 in which the second electrodes are a plurality of fine cathode wires with each cathode wire extending over a separate one of the indicia of the first electrode.

6. A display device in accordance with claim 5 in which the cathode wires are connected between spaced parallel mounting wires and the mounting wires are supporting on posts which extend and are secured into holes in the base plate.

7. A display device in accordance with claim 6 in which each of the cathode wires is connected at one end to a common first mounting wire, the other ends of some of the cathode wires are connected to a second mounting wire and the other ends of the other cathode wires are connected to a third mounting wire, the second and third mounting wires are mounted on the base plate in longitudinal alignment and parallel to the first mounting wire.

8. A display device in accordance with claim 4 in which each of the grids is a wire mesh having a metal mounting bracket at each end thereof, each of said mounting brackets is seated on and secured to a separate metal film mounting pad on the front surface of the base plate and one of the mounting pads for each grid is part of the electrical circuit means electrically connecting the grid to its termination pad.

9. A display device in accordance with claim 8 in which the termination pads for the grids are on one surface of the base plate and the termination pads for the interconnecting strips of the section of the first electrode are on the other surface of the base plate.

10. A display device in accordance with claim 2 in which the chamber between the cover and the base plate is filled with a gas which will break down when a bias is applied between the electrodes to cause the electrodes to glow.

11. A display device in accordance with claim 10 in each of the second electrodes are metal grids each of which extends across a separate one of the indicia of the first electrode and each of which is electrically connected to a separate termination pad.

12. A display device in accordance with claim 11 in which each of the grids has a metal mounting bracket at each end thereof, each of said mounting brackets is seated on and secured to a separate metal film mounting pad on the front surface of the base plate, and one of the mounting pads for each grid is part of the electrical circuit means electrically connecting the grid to its termination pad.

13. A display device in accordance with claim 12 in which the termination pads for the first electrodes are on one surface of the base plate and the termination pads for the second electrodes are on the other surface of the base plate. 

1. A display device comprising: an insulating laminated substrate having a plurality of lamina of insulating material bonded in face-to-face relation, a patterned first electrode on a front lamina surface of said substrate forming a plurality of indicia, a plurality of second electrodes mounted on said substrate disposed one each in spaced relation over each of said indicia, metallized paths extending along various inside facing lamina surfaces of said substrate, metal termination pads on a lamina surface in spaced relation to said metallized paths terminating along one edge of said substrate, and connection means extending through the lamina providing interconnections between various ones of said terminal pads and various ones of said indicia and said electrodes via said metallized paths.
 2. A display device comprising: a rigid base plate of a plurality of sheets of an electrical insulating material bonded together in face-to-face relation; a metal film first electrode coated on the front face of the front sheet of the base plate, said metal film electrode forming a plurality of identical indicia, each of said indicia comprising a plurality of sections disposed in pre-selected positions; a plurality of metal film interconnecting strips coated on an inside surface of one of said sheets of the base plate, each of said interconnecting strips being electrically connected through said front sheet to the similarly positioned electrode section of each of the indicia; second electrodes mounted on the front surface of the base plate and extending over the first electrodes; metal film termination pads coated on the base plate and terminating along one edge of the base plate; metal film electrical circuit means coated on the surface of the sheets of the base plate and extending through the sheets electrically connecting the inteRconnecting strips and the second electrodes to the termination pads; and a transparent cover mounted on the front surface of the base plate and forming a chamber with said base plate which contains the electrodes.
 3. A display device in accordance with claim 2 including a layer of an electroluminescent phosphor coated over the sections of the first electrode and a plurality of grids mounted on the front surface of the base plate with each of said grids extending over a separate one of the indicia of said first electrodes and under a second electrode.
 4. A display device in accordance with claim 3 including electrical circuits means on the surfaces of and extending through at least one of the sheets of the base plate electrically connecting each of said grids to a separate termination pad on said base plate.
 5. A display device in accordance with claim 4 in which the second electrodes are a plurality of fine cathode wires with each cathode wire extending over a separate one of the indicia of the first electrode.
 6. A display device in accordance with claim 5 in which the cathode wires are connected between spaced parallel mounting wires and the mounting wires are supporting on posts which extend and are secured into holes in the base plate.
 7. A display device in accordance with claim 6 in which each of the cathode wires is connected at one end to a common first mounting wire, the other ends of some of the cathode wires are connected to a second mounting wire and the other ends of the other cathode wires are connected to a third mounting wire, the second and third mounting wires are mounted on the base plate in longitudinal alignment and parallel to the first mounting wire.
 8. A display device in accordance with claim 4 in which each of the grids is a wire mesh having a metal mounting bracket at each end thereof, each of said mounting brackets is seated on and secured to a separate metal film mounting pad on the front surface of the base plate and one of the mounting pads for each grid is part of the electrical circuit means electrically connecting the grid to its termination pad.
 9. A display device in accordance with claim 8 in which the termination pads for the grids are on one surface of the base plate and the termination pads for the interconnecting strips of the section of the first electrode are on the other surface of the base plate.
 10. A display device in accordance with claim 2 in which the chamber between the cover and the base plate is filled with a gas which will break down when a bias is applied between the electrodes to cause the electrodes to glow.
 11. A display device in accordance with claim 10 in each of the second electrodes are metal grids each of which extends across a separate one of the indicia of the first electrode and each of which is electrically connected to a separate termination pad.
 12. A display device in accordance with claim 11 in which each of the grids has a metal mounting bracket at each end thereof, each of said mounting brackets is seated on and secured to a separate metal film mounting pad on the front surface of the base plate, and one of the mounting pads for each grid is part of the electrical circuit means electrically connecting the grid to its termination pad.
 13. A display device in accordance with claim 12 in which the termination pads for the first electrodes are on one surface of the base plate and the termination pads for the second electrodes are on the other surface of the base plate. 